﻿<!DOCTYPE html>
<html>
<head>
  <title>HTML Context Menu</title>
  <!-- Copyright 1998-2020 by Northwoods Software Corporation. -->
  <meta name="description" content="Context menus implemented in HTML rather than as GoJS objects." />
  <meta name="viewport" content="width=device-width, initial-scale=1">

  <style type="text/css">
    /* CSS for the traditional context menu */
    .menu {
      display: none;
      position: absolute;
      opacity: 0;
      margin: 0;
      padding: 8px 0;
      z-index: 999;
      box-shadow: 0 5px 5px -3px rgba(0, 0, 0, .2), 0 8px 10px 1px rgba(0, 0, 0, .14), 0 3px 14px 2px rgba(0, 0, 0, .12);
      list-style: none;
      background-color: #ffffff;
      border-radius: 4px;
    }

    .menu-item {
      display: block;
      position: relative;
      min-width: 60px;
      margin: 0;
      padding: 6px 16px;
      font: bold 12px sans-serif;
      color: rgba(0, 0, 0, .87);
      cursor: pointer;
    }

    .menu-item::before {
      position: absolute;
      top: 0;
      left: 0;
      opacity: 0;
      pointer-events: none;
      content: "";
      width: 100%;
      height: 100%;
      background-color: #000000;
    }

    .menu-item:hover::before {
      opacity: .04;
    }

    .menu .menu {
      top: -8px;
      left: 100%;
    }

    .show-menu, .menu-item:hover > .menu {
      display: block;
      opacity: 1;
    }
  </style>

  <script src="../release/go.js"></script>
  <script src="../assets/js/goSamples.js"></script>  <!-- this is only for the GoJS Samples framework -->
  <script id="code">

    var myDiagram = null;

    function init() {
      if (window.goSamples) goSamples();  // init for these samples -- you don't need to call this
      var $ = go.GraphObject.make;  // for conciseness in defining templates

      myDiagram =
        $(go.Diagram, "myDiagramDiv",  // create a Diagram for the DIV HTML element
          {
            "undoManager.isEnabled": true
          });

      // This is the actual HTML context menu:
      var cxElement = document.getElementById("contextMenu");

      // Since we have only one main element, we don't have to declare a hide method,
      // we can set mainElement and GoJS will hide it automatically
      var myContextMenu = $(go.HTMLInfo, {
        show: showContextMenu,
        hide: hideContextMenu
      });

      // define a simple Node template (but use the default Link template)
      myDiagram.nodeTemplate =
        $(go.Node, "Auto",
          { contextMenu: myContextMenu },
          $(go.Shape, "RoundedRectangle",
            // Shape.fill is bound to Node.data.color
            new go.Binding("fill", "color")),
          $(go.TextBlock,
            { margin: 3 },  // some room around the text
            // TextBlock.text is bound to Node.data.key
            new go.Binding("text", "key"))
        );

      // create the model data that will be represented by Nodes and Links
      myDiagram.model = new go.GraphLinksModel(
        [
          { key: "Alpha", color: "#f38181" },
          { key: "Beta", color: "#eaffd0" },
          { key: "Gamma", color: "#95e1d3" },
          { key: "Delta", color: "#fce38a" }
        ],
        [
          { from: "Alpha", to: "Beta" },
          { from: "Alpha", to: "Gamma" },
          { from: "Beta", to: "Beta" },
          { from: "Gamma", to: "Delta" },
          { from: "Delta", to: "Alpha" }
        ]);

      myDiagram.contextMenu = myContextMenu;

      // We don't want the div acting as a context menu to have a (browser) context menu!
      cxElement.addEventListener("contextmenu", function(e) {
        e.preventDefault();
        return false;
      }, false);

      function hideCX() {
        if (myDiagram.currentTool instanceof go.ContextMenuTool) {
          myDiagram.currentTool.doCancel();
        }
      }

      function showContextMenu(obj, diagram, tool) {
        // Show only the relevant buttons given the current state.
        var cmd = diagram.commandHandler;
        var hasMenuItem = false;
        function maybeShowItem(elt, pred) {
          if (pred) {
            elt.style.display = "block";
            hasMenuItem = true;
          } else {
            elt.style.display = "none";
          }
        }
        maybeShowItem(document.getElementById("cut"), cmd.canCutSelection());
        maybeShowItem(document.getElementById("copy"), cmd.canCopySelection());
        maybeShowItem(document.getElementById("paste"), cmd.canPasteSelection(diagram.toolManager.contextMenuTool.mouseDownPoint));
        maybeShowItem(document.getElementById("delete"), cmd.canDeleteSelection());
        maybeShowItem(document.getElementById("color"), obj !== null);

        // Now show the whole context menu element
        if (hasMenuItem) {
          cxElement.classList.add("show-menu");
          // we don't bother overriding positionContextMenu, we just do it here:
          var mousePt = diagram.lastInput.viewPoint;
          cxElement.style.left = mousePt.x + 5 + "px";
          cxElement.style.top = mousePt.y + "px";
        }

        // Optional: Use a `window` click listener with event capture to
        //           remove the context menu if the user clicks elsewhere on the page
        window.addEventListener("click", hideCX, true);
      }

      function hideContextMenu() {
        cxElement.classList.remove("show-menu");
        // Optional: Use a `window` click listener with event capture to
        //           remove the context menu if the user clicks elsewhere on the page
        window.removeEventListener("click", hideCX, true);
      }
    }

    // This is the general menu command handler, parameterized by the name of the command.
    function cxcommand(event, val) {
      if (val === undefined) val = event.currentTarget.id;
      var diagram = myDiagram;
      switch (val) {
        case "cut": diagram.commandHandler.cutSelection(); break;
        case "copy": diagram.commandHandler.copySelection(); break;
        case "paste": diagram.commandHandler.pasteSelection(diagram.toolManager.contextMenuTool.mouseDownPoint); break;
        case "delete": diagram.commandHandler.deleteSelection(); break;
        case "color": {
          var color = window.getComputedStyle(event.target)['background-color'];
          changeColor(diagram, color); break;
        }
      }
      diagram.currentTool.stopTool();
    }

    // A custom command, for changing the color of the selected node(s).
    function changeColor(diagram, color) {
      // Always make changes in a transaction, except when initializing the diagram.
      diagram.startTransaction("change color");
      diagram.selection.each(function(node) {
        if (node instanceof go.Node) {  // ignore any selected Links and simple Parts
          // Examine and modify the data, not the Node directly.
          var data = node.data;
          // Call setDataProperty to support undo/redo as well as
          // automatically evaluating any relevant bindings.
          diagram.model.setDataProperty(data, "color", color);
        }
      });
      diagram.commitTransaction("change color");
    }
  </script>
</head>
<body onload="init()">
<div id="sample">
  <div style="display: inline-block;">
    <!-- We make a div to contain both the Diagram div and the context menu (such that they are siblings)
         so that absolute positioning works easily.
         This DIV containing both MUST have a non-static CSS position (we use position: relative)
         so that our context menu's absolute coordinates work correctly. -->
    <div style="position: relative;"  >
      <div id="myDiagramDiv" style="border: solid 1px black; width:400px; height:400px"></div>
      <ul id="contextMenu" class="menu">
        <li id="cut" class="menu-item" onclick="cxcommand(event)">Cut</li>
        <li id="copy" class="menu-item" onclick="cxcommand(event)">Copy</li>
        <li id="paste" class="menu-item" onclick="cxcommand(event)">Paste</li>
        <li id="delete" class="menu-item" onclick="cxcommand(event)">Delete</li>
        <li id="color" class="menu-item">Color
          <ul class="menu">
            <li class="menu-item" style="background-color: #f38181;" onclick="cxcommand(event, 'color')">Red</li>
            <li class="menu-item" style="background-color: #eaffd0;" onclick="cxcommand(event, 'color')">Green</li>
            <li class="menu-item" style="background-color: #95e1d3;" onclick="cxcommand(event, 'color')">Blue</li>
            <li class="menu-item" style="background-color: #fce38a;" onclick="cxcommand(event, 'color')">Yellow</li>
          </ul>
        </li>
      </ul>
    </div>

    <div id="description">
      <p>This demonstrates the implementation of a custom HTML context menu.</p>
      <p>For a light-box style HTML context menu implementation, see the <a href="htmlLightBoxContextMenu.html">LightBox Context Menu</a> sample.</p>
      <p>Right-click or tap-hold on a Node to bring up a context menu.
      If you have a selection copied in the clipboard, you can bring up a context menu anywhere to paste.</p>
    </div>
  </div>
</div>
</body>
</html>